The book offers background material for explaining a number of
astronomical concepts. The stellar multiplicity and the various
mechanisms of binary formation are perhaps the most obvious
ones. A suitable topic for discussion in class is the validity
of the fictional hypothesis, explaining the existence of the
accreted part of the Proxima's planetary system: is it
realistic in the light of the more recent – with respect to
the publication year of the novel – discovery that the chemical
composition of Alpha Cen A and B is different than that of
Proxima? This was found during detailed abundance analysis of
the three stars: [Fe/H]=0.22\(\pm \) 0.10 to 0.26\(\pm \) 0.08
[1]} for Alpha Cen A and B, and
[Fe/H]=\(-\) 0.07\(\pm \) 0.14 [2]} to
0.05\(\pm \) 0.20 [3]} for Proxima (the
statistical significance of that difference is yet another
topic for discussion that I will only point at here). This
implies that
while the central pair has formed together, while Proxima is a
later acquisition, most likely being accreted during a stellar
flyby. The time of this flyby is unknown, but the probability
that it might have happened early enough while the central
binary still had multiple planetesimals is low, just because
this is a short period – of up to a few tens of millions of
years
[4]}, [5]} – with respect
to the billion year age of the two main stars in the system.
Dynamic studies of the Alpha Cen system also favor different
origin of its components [6]}.
